A combined module of a folding container is conventionally known in which long-side bank portions of a bottom of a large folding container are formed to be lower than short-side bank portions of the bottom (for example, the Unexamined Japanese Patent Application Publication (Tokkai-Hei) No. 2002-2696).
In the prior art, since the long-side bank portions of the bottom of the large folding container are formed to be the lower than short-side bank portions of the bottom, the bottom of the large folding container has insufficient strength and rigidity. Consequently, the large folding container is likely to be deformed when subjected to a load or twisted. This problem is more serious if a small folding container is stacked on the large folding container.
It is an object of the present invention to solve the above problem of the conventional combined module of the folding container.